Processes for quaternizing amines and imidazoline compounds are known in the art. U.S. Pat. No. 4,529,803, July 16, 1985, Tomalia et al., and U.S. Pat. No. 4,267,350, May 12, 1981, Tomalia et al., disclose a process for preparing an imidazolinium amide salt by (1) reacting an imidazoline with an .alpha., .beta.-unsaturated ester of a carboxylic acid; (2) reacting the resulting ester imidazoline with a primary or secondary amine; and (3) quaternizing the resulting amide imidazoline product by reacting it with an alkylating agent.
U.S. Pat. No. 4,238,373, Dec. 9, 1980, to Hardy et al., discloses a process for quaternizing tertiary amines in an organic reaction medium comprising a water-soluble or water-dispersible organic compound having a molecular weight greater than 240. The quaternization reaction is carried out by first mixing a tertiary amine containing one or more long chain hydrocarbon residues with the organic reaction medium. This mixture is agitated and the quaternizing agent is then introduced into the mixture in an amount in excess of that stoichiometrically required. The quaternization reaction of this reference may proceed under both anhydrous and aqueous conditions.
U.S. Pat. No. 4,339,391, July 13, 1982, Hoffmann et al., discloses quaternary ammonium compounds, which may optionally contain ester-interrupted alkyl substituents, and methods for their preparation and use. In the disclosed preparation method, an aminoalkylate is reacted with a free fatty acid, without solvents, to form an intermediate amine. The intermediate amine is then dispersed in water and is quaternized with a quaternizing agent. The quaternization may be carried out either in the presence of a lower alcohol solvent or in the absence of such solvent.
German OLS 2430140, published Feb. 19, 1976, assigned to Rewo Chemische Fabrik GmbH, discloses diester quaternary ammonium compounds and several methods for their preparation, including a quaternization method which does not require using a solvent during the quaternization reaction.
British Patent Specification 980,003, Jan. 13, 1965, assigned to L'Oreal, discloses a method of preparing a quaternary ammonium compound wherein quaternization is accomplished by adding a stoichiometric quantity of dimethylsulfate to an amino ester solution containing, among other ingredients, isopropyl alcohol and an amino ester.
Many different types of fabric conditioning agents have been used in rinse-cycle fabric treatment compositions. One class of compounds frequently used as the active component for such compositions includes substantially water-insoluble quaternary nitrogenous compounds having two long chain alkyl groups. Typical of such materials are ditallow dimethyl ammonium chloride and imidazolinium compounds substituted with two long chain alkyl groups. These materials are normally prepared in the form of a dispersion in water.
The use of substituted imidazoline compounds as fabric conditioning agents is known. Imidazoline compounds have been used by themselves or in combination with other agents in the treatment of fabrics. British Patent Specification 1,565,808, issued Apr. 23, 1980, and assigned to Hoechst Aktiengesellschaft, discloses a textile fabric softener composition consisting of an aqueous solution or dispersion of an imidazoline or salt thereof, or a mixture of such imidazolines or salts thereof. U.S. Pat. No. 4,724,089, Feb. 9, 1988, to Konig et al., discloses fabric treatment compositions containing dialkyl imidazoline compounds, or salts thereof, which may have one alkyl chain interrupted by an ester linkage.
The use of imidazolinium salts as fabric conditioning agents is also known. U.S. Pat. No. 2,874,074, Feb. 17, 1959, to Johnson discloses using imidazolinium salts to condition fabrics. U.S. Pat. No. 3,681,241, Aug. 1, 1972, to Rudy, discloses fabric conditioning compositions containing a mixture of imidazolinium salts and other fabric conditioning agents.
It is generally known that when quaternizing imidazoline amide compounds, the imidazoline compound must be in a state wherein it can react with the quaternizing agent. Such a reactive state may be achieved by liquifying the imidazoline through melting or by dispersing or dissolving the imidazoline in a solvent. Lower alkyl (i.e., C.sub.1 -C.sub.4) alcohol solvents are typically used for this. However, when quaternizing an imidazoline ester compound, the presence of such lower alcohol solvents can cause transesterification reactions between the imidazoline ester compound and the lower alcohol solvent.
Additionally, the presence of water during quaternization of an imidazoline ester compound can cause hydrolysis of the imidazoline ester reactant prior to quaternization.
It is therefore an object of the present invention to provide a process for quaternizing an imidazoline ester compound in the absence of lower alcohol solvents and water.
It is another object of this invention to provide a high yield process for preparing a reaction product containing a quaternized imidazoline ester compound and, optionally, an imidazoline ester compound.
It is another object of this invention to provide a process for preparing said reaction product containing a quaternized imidazoline ester compound and, optionally, an imidazoline ester compound at optimum relative concentrations without the need for additional processing.
These objects are realized by the present invention.